Big_C

I just got my new 355 motor in my 89 firebird and now when I hit the gas and my one wheel breaks loose, it hopps all across the road. Ive been told that this is called wheel hop and it is a commen problem. How do you get rid of it? Im planning on installing a 3.42 posi, subframe connectors, high pressure drag shocks, maybe new springs and a set of ET street racing tires. Will these mods get rid of it??

DuronClocker

iTrader: (1)

Buy tubular lower control arms and a polyurethane torque arm bushing at least. Ideally, buy an aftermarket adjustable torque arm.

Once I put my new springs and shocks in, I started getting wheelhop on my 275/40R18 Eagle F1's. Replaced the torque arm mount with a polyurethane one, and I have no wheelhop at all anymore. Still have to install my tubular lower control arms. I'm waiting to do this until I install a new rearend.

83 Crossfire TA

iTrader: (2)

Wheelhop = something is loose or broken.

Throwing parts at it will not fix it unless the parts replace whatever is loose/broken,b ut it's usually easier/cheaper to just figure out what's wrong.

RB83L69

Wheel hop = you need LCA lowering brackets

Assuming of course, there's nothing broken or defective or just plain worn out.

One of the cheeeeepest mods you can do to these cars, VERY high on the "bang/buck" list. They repair the defective design that results in backwards geometry, whereby whenever the rear tires get a good bite, they try to lift the rear off the ground.

83 Crossfire TA

iTrader: (2)

Wheelhop <> LCA relo brackets

Yea, they do dramatically change the IC and antisquat. Also nothing to do with wheel hop. Dramatic increases in antisquat pretty much requires big, soft slicks to absorb the extra energy. In a handling application it also means turn in oversteer, which can be pretty dramatic when you find that the car wants to loop when you want to go hard into a corner and then understeers when you give it throttle coming out and expect oversteer.

Yes, they do work (the reason that I’m putting adjustable pick up points on the brackets on my 9”), but they are not some miracle solution. Honestly, they’re better applied to the fox/sn mustang chassis where they not only increase antisquat but can actually improve turn in.

RB83L69

Wheel hop = needs LCA lowering brackets

It goes beyond changing the instant center. In these cars, the rear mount point for the LCA, is above the front mount point, on the frame. Sooo, imagine what happens as the rear starts to push the car. Since the rear end end of the LCA (the pushing end) is ABOVE the frame end (the pushed end), whenever the rear end begins to try to push the car, the inescapable natural tendency in the system, is for the rear to try to rotate upwards. So: you mash the gas, drop the clutch, whatever; maybe you're lucky or you've installed slicks, and your tires bite; the rear begins to push the car; the rear tries to rotate upwards, around the front LCA bolts as its arc center; the tires unload; the traction disappears; the tires spin; the pushing force goes away; the springs begin to push the rear back down; the tires eventually bite; the pushing force is restored; the rear tries to rotate upward; etc. etc. etc. About 5-7 times a second.

That's "wheel hop", in a nutshell.

Wheel hop = needs LCA lowering brackets

LCA RBs repair the defective geometry

The effects on handling are alot less pronounced; mostly they tend to tighten the car up (add oversteer) under power because they ..... {drum roll please} make the rear hook up!!!. Imagine that. If you autocross the car or the like, you'll probably want to decrease your front sway bar or increase the rear one.

83 Crossfire TA

iTrader: (2)

That’s a cute explanation, but one that only makes sense if you greatly distort the rear suspension geometry. Even severely lowered with the stock pickup points, it’s difficult to get the LCA angles in excess of 3*. Try it and measure it. you’ll manage to get it to around 4-5* if you remove the rear springs and let it rest on the bump stops. That adds up to just about nothing in your explanation (ie, not enough to make sense).

Real world… I own 3 f-bodies. The tallest one sits at about the same ride height as a set of eibach pro springs. The other 2 sit much lower. Only the tallest has LCA brackets (although the the LCAs are still in the original pivot hole). None have ANY signs of wheel hop, the only time that any of them did was when the tallest one didn’t have one of the pivot bolts on one of the LCA’s torque properly. All have stock TA’s and TA mounts, 2 have some form of reinforced (boxed) LCA, one doesn’t, 2 (not the same 2) have either an aftermarket PHR or a boxed stock PHR. All the factory components (besides the boxed PHR) still have factory rubber bushings. All will run low 1.7 60’s on street radials, much faster on real drag tires.

If your theory of what LCA relo brackets do to the suspension geometry is correct then explain why none of my cars wheel hop?



Calling it defective is quite arrogant. Some of these cars left the factory with nearly as low a ride height as what most people lower them to and the geometry was designed as it was for a reason. It would have been no problem at all for GM to change the pivot locations if it didn’t intend the geometry as it was. And before you say it, this is quite different an issue then the relative flexablility of some of the suspension parts or chassis.

¿Que?

How about trying that again, you contradicted yourself at least 3x in 1 sentence (more, depending on how you want to count it).

“tightening up” would be adding understeer/lessening oversteer, not adding oversteer as you stated

“rear hook up” again, less oversteer not more

the geometry change would actually produce corner entry oversteer and exit understeer as I’ve already stated.

If they actually cause the back end to “hook up” then you’d want to INCREASE your front sway bar to transfer more weight to the diagonally opposite rear wheel to take advantage of your new found traction, this would help on corner exit with LCA brackets but hurt on entry.

RB83L69

I'm sorry, I must have got a brain cramp right then, I meant "add understeer"... they make the rear hook up and go straight, which makes the front have to do more work to turn.

I apologize for the mistake.

As far as the rest of it, believe whatever you like, and be as smug about what your car does or doesn't do as you like; I'll go with what works. I'll be hoping you're the guy in the other lane.

The suspension design is defective for the usage at hand. That is not arrogant. The factory no doubt did what they did for whatever reasons they had for doing it, which may or may not be the same as the usage the rest of us want to put the car to. Basically, the same reason we modify anything. If it was perfect to begin with, we wouldn't need to modify it.

All this drivel about rubber bushings in the Panhard bar has nothing to do with wheel hop.

Wheel hop isn't an issue in corner entry for most people; it's a problem IN A STRAIGHT LINE. All this other drivel about corner entry is beside the point.

Wheel hop = the car needs LCA lowering brackets

83 Crossfire TA

iTrader: (2)

I believe in what works… I also believe that I get consistently better 60’s on radials then just about anyone on this board, and probably have 400 timeslips to show for it.

I’m not being smug, just that I’ve been through this with dozens of f-bodies and always get the same results… someone tells me that “the car is perfect and it gets wheel hop.” After going back and forth for a while they finally show it to me and there is always something wrong causing the wheel hop. Always.



And that was my point in pointing out that this is different then the stamped steel suspension parts…. I’d buy your argument if you could give me a good argument for what GM has to gain by building the car with “defective” suspension geometry.



The pahnard is probably the only stock piece that even when in decent shape may cause wheel hop. Usually on a more powerful car you’ll see it in the 1-2 shift first (the car will jump sideways like 4’), and it will get worse as you try to apply a lot more power.

If all you’re going to do is go in a straight line on slicks then LCA brackets are a good idea, if you’re going to turn you have to weigh the advantages with the disadvantages. With most LCA relo brackets you get 2 pivot points, one 2” and one 3” below the stock pivot. With most lowered cars that are still expected to handle well, a pivot about 3/4-1.5” below the stock location would be optimum… 2” is too much. Like I said, I’ve got a set of spohn brackets on one of my cars, and I don’t use them. I made my own brackets for my 9” and it has pivot holes spaced every 1 from the stock location to 3” below stock. Depending on the tires that I run at the dragstrip, I’ll probably run it in the 2” down most of the time and swap it to the 1” down when I go autox or if it’s going to see a lot of street time on smaller tires, but this is for antisquat reasons, wheel hop is not an issue.

As far as wheel hop on a handling application… try corner exit on a tight autox with a car that has rear axle wheel hop.

RB83L69

Go back to the beginning. What did this guy ask? What is he doing with his car? What kind of shocks did he mention? What kind of tires does he talk about?

So what does all this "autocross" drivel have to do with what he asked?

I don't want to come across like a jerk; but this is beginning to get a bit tiresome.

The Panhard bar has nothing to do with straight-line wheel hop.

Wheel hop is caused by incorrect rear lower control arm geometry resulting from flawed design, and aggravated by lowering the car in cases where that's been done.

It's fixed by LCA lowering brackets.

Sure fixed the hell out of mine, after NOTHING else even dented it. Including a Spohn torque arm, better LCAs, SFCs, and a handful of other improvements to the vehicle. Each of those other mods had positive effects, but THE ONE that fixed wheel hop, was LCA lowering brackets.

End of story.

phoenix305

Man you guys know alot about suspension! So just plain and simple what causes wheel hop on this type of suspension? And in a leaf spring type suspension isn't it the leaf spring binding that causes wheel hop?

RB83L69

I forgot what causes it in these cars. But I'll go back and re-read my 2nd post, it's in there somewhere.

In leaf spring vehicles, it's a number of things; spring wrap is one, the rear eye bolt being lower than the front bolt (the same type issue as these cars, in effect), and a few other things.

phoenix305

no need to be a dick about it. You did state it but other people contridicted your points so i'm not quite clear on who's right. but thanks for being so nice.

RB83L69

Hey, no problem.... and, I'm really really trying hard not to be a jerk. But it's incredibly difficult sometimes.

If you'd like to see who's right about this, all you gotta do, is take a car that wheel-hops, and stick some LCA lowering brackets on it. You'll know the first time you let out the clutch who has the correct answer. Won't take you 10 seconds to figure it out.

They have to be by far the biggest bang-for-the-buck traction mod there is, for a 3-link setup like ours. In fact they work wonders for some 4-link systems too, depending on their geometry. Old Chevelles benefit from them for example.

83 Crossfire TA

iTrader: (2)

he mentioned it bouncing across the road.



Try reading everything and determining the context of the answer before jumping off on conclusions



Yes, it does. I’ve already specified how, where and why. Of course, unless the car is running 11’s or so with an auto or just about as fast and you’re powershifting with a stick you’ll never see it. If you’ve got wheel hop and are running slower your car is broken. Plain and simple. Figure out what is wrong and fix it.

Yea, you probably had a loose pivot bolt a worn out spot on a shock or something along those lines, removed it when putting the LCA brackets and then tightened it up when you reinstalled. Wheelhop is gone and you’re attributing it to the wrong change.



To hear people talking about this on this board you’d think that all of these cars wheel hop, all the time. I’d bet that less then 5-10% of people every see wheel hop. If you what to see wheel hop mess with something with an IRS like a GTO or a 350Z/G35. You give them enough power and you have wheel hop. Not really much you can do about it, it’s a suspension geometry problem.

These 3rd and 4th gen f-bodies don’t have wheel hop problems, they’ve got worn suspensions that have been used hard that need maintenance.

If any of you are local you’re welcome to stop by and take a look at what I’ve got that doesn’t wheel hop. And if you have wheel hop I bet that I’ll find the reason in a matter of minutes…

Oh man… where’d you get a 3 link from… if you want to know what a 3 link is then check out a diagram of an ’05 mustang.

Big_C

Wow, thanks for the replies. I didnt want anyone to start anything hostile though. I just thought I would add that Im building the car to run straight line drags on the street and strip. Im not planning on doing any sort of autocross or anything.

DuronClocker

iTrader: (1)

I can understand the logic in the rotating of the rearend and unloading to cause wheelhop, and I could theoretically see the benefit of LCARBs, but as stated, these cars shouldn't wheelhop unless something is worn out.

My car never wheelhopped until I lowered the back with DropZone springs. Inspected a few things and noticed that my torque arm mount was severely worn. The stock rubber pieces in these cars are sooooo soft its disgusting. Replaced with a polyurethane mount and wheelhop problems were eliminated.

Granted, my car isn't pushing any crazy numbers or any crazy 60' times, but it still experienced wheelhop and was easily fixed by replacing my torque arm mount. When diagnosing wheelhop, before telling to throw LCARBs on, tell someone to check all of their bushings to make sure nothing is too terribly worn, check for loose bolts, and check condition of shocks.